1. Field of the Invention
The present invention relates to a variable compression ratio apparatus of an exhaust gas brake, and more particularly to a variable compression ratio apparatus of an exhaust gas brake that is capable of efficiently performing a brake operation.
2. Description of Related Art
Generally, because a full-sized vehicle, namely a truck or a bus, is very heavy due to its own weight or cargo, it is required to reduce a load of an engine brake so as to maintain stability thereof.
For this reason, a separate valve, i.e., a third valve, is further mounted at a plurality of cylinders having an intake valve and an exhaust valve, and the third valve is opened at nearly top dead center (TDC) of a piston when driving, and then compressed air in the cylinders is exhausted out of each cylinder.
Conventionally, the engine brake is classified as a jake brake and a bleed brake for exhausting exhaust gas out of the cylinders.
The jake brake indicates that an exhaust valve is temporarily opened at the late part of a compression stroke of a piston for offsetting compression pressure, and subsequently suppresses an inertial force for braking.
Further, the bleed brake indicates that the exhaust valve is continuously opened at the compression stroke of the piston, and thereby it performs the same function as that of the jake brake.
The conventional structure has an advantage of improving an engine brake performance by changing a cam profile of the cam shaft and exhausting compressed air out of the cylinders, however, the structure is complex and manufacturing cost is increased.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.